Touch pressure with felt tip marker on petri dish registers cumulative count on the digitaldisplay with confirmation by audible tone (can be turned on or off). The pressure required to register a count can be adjusted to suit each user.Averaging facility calculates average count over multiple plates. Counting results as well as useful statistics including SD can be sent directly to the accessory printer or to a computer via a USB cable supplied.Sub-stage illumination by low energy bright LED's allows glare-free optimum viewing. A switchable black background is provided to enhance viewing of translucent and difficult to see colonies. Supplied with two Wolffhuegel graticules and dish centering adapters to facilitate use with 50mm to 90mm dishes. A choice of magnifiers and a printer are available as optional accessories.